Unmanned Systems Technology 009 | Ocean Aero Submaran S10 | Simulation and testing | Farnborough report | 3W-110xi b2 TS HFE FI | USVs | Data storage | Eurosatory/UGS 2016 report

56 August/September 2016 | Unmanned Systems Technology Specification 110xi b2 TS HFE FI UAV engine Horizontally opposed twin 45 mm (1.77 in) x 35 mm (1.38 in) = 111.3 cc (6.79 cu in) Naturally aspirated Gasoline through heavy fuel (including JP5 and JP8) All-aluminium structure Linerless Three main bearings, roller Steel crankshaft, two pins Steel con rods Light alloy pistons; one ring Two plugs per cylinder option Reed valve Electronic ignition Fuel injection Engine management system 12.5:1 compression ratio Maximum rpm, 13,000 (normally 8500 rpm) The 110xi b2 TS HFE FI is a horizontally opposed twin with combined cylinder barrel and head units flanking the crankcase. Its structure is all aluminium. The crankcase is in three sections, with a generator housing on one end and a snout on the other. Within the generator housing the rotor is attached by six bolts to a flange on the crankshaft, while the stator is carried by the housing. The snout section is an aluminium casting attached by eight bolts to the main crankcase. It carries a Hall effect crankshaft speed sensor. Beyond the snout is an aluminium hub that fits over a taper on the nose of the crankshaft, with a single bolt securing it. The propeller is attached to this hub by six bolts. The built-up forged steel crankshaft runs in four main bearings, all 15 mm in diameter. The two centre bearings are 10 mm wide, whereas the outer bearings – one in the generator housing and one in the snout – are 8 mm wide. The crankpins are 15 mm wide with a 20 mm diameter. The crankshaft is driven by forged steel con rods using needle roller bearings. The steel piston pin, which has a very tight tolerance in its bores, is 25 mm long with a 14 mm diameter and is through-drilled to save weight. It runs in a single ring aluminium alloy piston. A single central reed housing sits atop the main crankcase. It is an aluminium alloy casting and is attached via four bolts. In turn, above the reed housing is an aluminium throttle body machined from solid with a single butterfly. A single injector feeds into the throttle body downstream of the butterfly. The ECU directly controls the fuel injector and an electric fuel pump. Pump location is decided in conjunction with the customer, to suit the specific UAV. Twin NGK M10 spark plugs are normally used, and each plug has its own coil, which is directly fired by the ECU. The ignition coils are located in two boxes, both boxes serving both cylinders so that if one should fail the engine will continue to fire on both cylinders. Each cylinder has its own exhaust, and the pipes are routed under the base of the crankcase to warm the crankcase above and fuel lines below. The 110xi weighs 4.9 kg including everything except the generator and the propeller. The engine is located in the airframe by anti-vibration mounts. Located on the opposite side to the propeller, the generator housing incorporates four mounts. To strip and rebuild this engine takes no more than three hours. Anatomy 3W’s110xib2 TS HFE FI is a compact package